Plastic mortar shell



May 4, 1965 w. E. ANTHONY PLASTIC MORTAR SHELL 3 Sheets-Sheet 1 Filed Jan. 2, 1962 ATTORNEYS MAI/4911115} Alma? BY %WWAWL, 0%? ZMZMM,

May 4, 1965 w. E. ANTHONY PLASTIC MORTAR SHELL 5 Sheets-Sheet 2 W M QW y 1965 w. E. ANTHONY 3,181,465

PLASTIC MORTAR SHELL Filed Jan. 2, 1962 3 Sheets-Sheet 3 ll: I; 4.82

INVENTOR. M4 4 MM 5% r/m/vr United States Patent 3,181,465 PLASTIC MQRTAR SHELL William E. Anthony, Box 2485, Gastonia, NC. Filed Jan. 2, 1962, Ser. No. 163,407 7 Claims. (Cl. 102-41) This invention relates to mortar shells and has particular reference to a new and improved dual-purpose mortar shell which is particularly adapted for both training purposes and combat use.

The experience gained in training of military personnel in the use of mortar weapons has resulted in a well defined need for devices which simulate service or battle conditions, as actual service rounds are unsafe, expensive, and otherwise impractical to use for this purpose. To be truly worthwhile, such training devices should impart a sense of reality to personnel undergoing training, stimulating a high degree of interest and enthusiasm.

In my copending application Serial No. 46,181, filed July 29, 1960, now Pat. No. 3,094,934, there is disclosed a mortar training shell which is particularly adapted for training purposes, wherein conventional shell casings are utilized to gain experience, while a new and improved means is provided for reclaiming and reusing these mortar shells after firing.

While the invention described in this copending application has enjoyed highly successful results, the present invention approaches the problem of providing a dualpurpose mortar shell from a difierent standpoint.

According to this invention there is provided a far simpler and more inexpensive dual-purpose mortar shell than heretofore known in the art, the mortar shell having a body of new and improved construction.

Another object of this invention is to provide a mortar shell having a body of inexpensive plastic material provided with a longitudinally elongated annular recessed portion or cavity in its side wall, such cavity being closed at its rearward end. Preferably, the annular cavity is open at its forward end and adapted to be closed by a novel adapter head, which in turn, carries a fuse head assembly.

Still a further object of this invention is to provide a mortar shell having a body with a hollow side wall defining an annular cavity, such cavity selectively carrying a fragmentation sleeve of novel construction for combat purposes; or a filler, such as sand, for training purposes.

A further object of this invention is to provide a lightweight and inexpensive mortar shell having a plastic body with a longitudinally extending annular recess in its side Wall, together with an elongated adapter head of cooperating configuration for enhancing the overall explosive capabilities of the shell.

Yet another object of this invention is to provide a mortar shell having a body of plastic material carrying a new and improved gas sealing means about the periphery thereof for engaging the interior walls of the mortar barrel during initial propulsion thereof from the barrel.

These and still further objects, advantages, and novel features of the present invention will become apparent in the specification and claims, taken with the accompanying drawings.

In the drawings:

FIGURE 1 is an exploded perspective view of a mortar shell according to one embodiment of this invention;

FIGURE 2 is a longitudinal sectional view of the assembled mortar shell in FIGURE 1 carried in a mortar barrel;

FIGURE 3 is a fragmentary view corresponding to FIGURE 2 showing a modified construction;

FIGURE 4 is an enlarged fragmentary sectional view of a portion of the assembled shell of FIGURE 1 illustrating the action of an interior high explosive charge in the shell;

FIGURE 5 is an enlarged fragmentary sectional view of a portion of FIGURE 3;

FIGURES 6 and 7 are enlarged fragmentary sectional views of FIGURE 2 and illustrating the action of the gas sealing means carried by the mortar shell body;

FIGURE 8 is a view corresponding to FIGURE 2 but showing a modified adapter head to increase the explosive charge carried by the shell;

FIGURE 9 is an elevation section view of a modified shell assembly; and

FIGURE 10 is an elevation section view of an arrange ment for molding the shell body.

Referring now to the accompanying drawings, there is shown in FIGURES 1 and 2 a mortar shell 16 which includes a shell body 12 carrying a conventional tail assembly 14 to which is adapted to be attached a conventional propulsion charge (not shown). The tail assembly 14 has a threaded stub shaft 16 in engagement with an interiorly threaded socket 18 at the rear end of the body 12 as best shown in FIGURE 2. The shell body 12 is of a lightweight, plastic construction, preferably high impact styrene; or alternatively, nylon, fiberglass, phenolic plastic, or the like. FIGURE 2 shows the shell 10 received within a mortar barrel 20.

The shell body 12 is hollow to provide a central explosive chamber 22 open at its forward end. The body also is of hollow or double wall construction having inner and outer walls 24 and 25 integrally joined at their rearward ends to define an annular recess or cavity 26 having an open forward end. The annular cavity 26 may carry a fragmentation sleeve 28, when the shell is used for combat purposes. The sleeve 28 is of cast-iron or other suitable metal construction, and has exterior circumferential and longitudinal grooves 30 and 32 respectively, and aligned interior circumferential and longitudinal grooves 30, 32' respectively. The sleeve 28, of course, is slidably received in the forward end of the cavity 26.

The forward end of the cavity 26 is closed by an adapter head 34 of frusto-conical configuration. The head has a longitudinal through passage 38 and a rearwardly extending reduced hollow extension or tubular boss 36 threadedly engaged within the forward end of the shell body 12, i.e. within the forward end of the inner wall 24. Conveniently, the rearwardly facing shoulder 49 of the adapter head 34 has a shallow annular recess or groove 42 aligned with the annular recess 26 of the body 12, such groove receiving the forward end of the fragmentation sleeve 28, as is apparent. The forward end of the head 34 is interiorly threaded to receive a fuse head assembly 44, also mainly of plastic.

The fuse assembly, which is similar to that disclosed in my aforementioned application, has a longitudinal through passage 50 having a counterbored and interiorly threaded forward end 51. A firing pin 52 is molded in a threaded plug 53 received in the counterbored portion 51 of the passage 50, and projects rearwardly into the longitudinal passage 5% A blank service cartridge 54, e.g. cal. .45, is slidably carried in the longitudinal passage 51! with its primer end facing the firing pin. A transverse passage 46 in the fuse 44- intersects the passage 50 and receives a cotter pin 48 to separate the cartridge 54 from the firing pin 52. The rearwardmost end of the fuse head 44 has a reduced threaded extension 56 which engages a shear cap 58, the cap 58 also serving to retain the cartridge 54 within the longitudinal passage 59.

The exterior peripheral surface of the shell body 12 carries a plurality of longitudinally-spaced integral gas check rings 60 for properly spacing the mortar shell It) within the mortar barrel 20. The rearwardmost ring 62 has a rearwardly diverging wall 64, best shown in FIG- URES 6 and 7, this rearward ring 62, because it is of somewhat flexible plastic, providing a flexible gas seal with the mortar barrel 20, as will become apparent.

Referring now to FIGURE 3, a slightly modified embodiment of the shell body is shown wherein the cavity 26 is omitted and the frangible sleeve 28 is molded into the shell body 12 and fixed therein in engagement with a rear circumferential wall 66 and a forward circumferential wall 68 to form a liner for the explosive chamber 22. In the embodiment of the invention shown in FIGURE 3, the frangible sleeve 21', of course, is in direct contact with an explosive charge (not shown) carried within the chamber 22. The forward end of the shell body 12 is interiorly threaded, as at 69, for the reception of the extension 36 of the adapter head 32, exactly as in the embodiment shown in FIGURE 2.

FIGURE 4 shows the inner wall 24 of the embodiment of FIGURES l and 2 deformed into the grooves 36 and 32 of the fragmentation sleeve 28 by the action of an explosion within the chamber 22; while FIGURE 5 is a similar view but shows the lines of force imparted normal to the side walls of the grooves 30' and 32 by a similar explosion in the embodiment of the invention shown in FIGURE 3.

FIGURES 6 and 7 show respectively, the rearwardmost ring 62 of the shell body 12 in a relaxed state during insertion into the barrel 2t); and, the ring 62 deflected and deformed outwardly against the inner surface of the barrel 20 by propulsion gases in the latter acting on the inclined wall 64. Thus an effective gas seal is provided by virtue of the configuration of the ring 62, together with its somewhat stiff but yieldable or resilient plastic construction. I

In FIGURE 8, there is shown a modified greatly elongated tubular adapter head 70 which includes an outer wall 72 and an inner wall 74 integrally joined at their forward ends in concentric, spaced-apart relationship to define a longitudinal annular recess or cavity 76 which is a.igned with the annular recess 26 of the shell body 12. At its rearward end the inner wall 74 carries exterior threads 78 for engagement with the interior threads at the forward end of the shell body 12. The forward end of the adapter head 70 is otherwise of generally similar construction to the adapter head 34 shown in FIGURES 1 and 2.

As previously mentioned, the mortar shell according to this invention, being of very inexpensive construction, is equally well suited for combat or training purposes. In training, the shell i employed as shown in FIGURE 2 with the chamber 22, being partially filled at its rearward end with plaster of Paris or the like (not shown) and also carrying a spotting low-order explosive charge of black powder or the like (not shown) in the forward end thereof. The annular space 26, if necessary, may be filled with sand or the like to provide the desired weight to the shell It).

The fuse head 44 is assembled as shown in FIGURE 2 with the plug $3 screwed into the forward end 51 of the passage 56, and a service cartridge 54 is retained in the passage 30 by the shear cap 58 and maintained out of contact with the firing pin 52 by the cotter pin 48. The fuse head 44 is threaded to the adapter head 34, which in turn, is threaded into the shell body 12. The necessary propelling charge (not shown) is fastened to the tail assembly 14. The cotter pin 43 is then removed from the transverse passageway 45 and the shell is dropped into the barrel 20.

The propelling charge is fired by conventional means which expels the shell from the barrel 20. While the shell is still within the barrel 20, the propulsion gases are sealed therein. In this regard, the rearwardly diverging wall 64 of the rearwardmost ring 62 is flexed outwardly from the relaxed position shown in FIGURE 6 to the position shown in FIGURE 7 by the action of the propulsive gases, thereby engaging with inner surfaces of the barrel 2% to effect a gas seal.

The acceleration of the shell 10 during flight holds the cartridge 54 in its rearwardmost position, but upon impact of the shell with a target, the cartridge 54 moves forward and engages the firing pin 52 and is detonated. The resulting expanding gases shear off the cap 58 from the threaded extension 56, allowing the gases to escape into the chamber 29 and thereby ignite the spotting charge carried at the forward end thereof. The resulting explosion breaks the shell body 12, providing a visible spotting charge at the point of impact of the shell lit) with the ground at some remote distance from firing.

This realistic explosion stimulates interest and enthusiasm among personnel as there is a visible indication of a simulated explosion.

In actual combat use, the same type shell is utilized, the shell carrying a high explosive charge in the chamber 22 and the fragmentation sleeve 28 being inserted in the annular recess 25. The shell 1% is fired, as previously described, and when, on impact, the fuse head 44 ignites the charge of high explosive in the chamber 22, there is, of course, a tremendous pressure created. This pressure is exerted on the fragmentation sleeve 28, and normally against the side walls of the grooves 30', 32. Referring to FIGURE 4, the outward force 'of the gases acts on the interior surface of the wall 24 and deforms the latter into the grooves 31), 32' of the sleeve 28. In FIGURE 5, the grooves 3t), 32' are in direct contact with the explosive gases, as is apparent. Due to the distribution of force in angularly opposed relationship along the side walls of the grooves 39', 32, the sleeve 28 is fractured along these grooves in a notably superior manner, as the oppositely directed lines of force tend to break up the frangible sleeve 28 at these grooves, providing a superior shrapnel effect. The cooperating external grooves 30, 32, of course, further enhance this action as the sleeve 28 is substantially weakened in these regions.

Due to the saving in weight of the mortar shell it) by virtue of the plastic construction, a greater explosive charge may be carried for a given propulsion charge.

Thus, the adapter head '79 may be mounted between the fuse head 44 and the shell body 12 in place of the adapter head 34. In this embodiment of the invention, the frangible sleeve 28 would be of corresponding length, as is apparent, and the entire enlarged chamber 22 is filled with explosive.

Referring now to FIGURE 9, the shell body generally similar to that shown in FIGURE 3, carries a fuse head assembly 44 adjacent the forward end of the body. In this regard, the adapter head is formed of metal and is threaded to the interior threads 69 in the forward end of the shell body. As will be appreciated, the adapter heads of varying exterior thread size can be conveniently maintained in stock so as to accommodate a fuse head assembly 44- of one size only to shell bodies 12 of varying size.

In FIGURE 10, the shell body 12 is formed in a split mold 8t which conforms to the exterior configuration of the body 12. Suitable conduit means 82 provide communication with the interior thereof for filling the mold. The split mold fit) has a threaded opening 32 receiving a male 1016. form 84 having a cooperatively threaded portion 6. The mold form 8 includes a curved projecting portion 85, and the recessed walls 66 and 68 are conveniently formed by split ring segments 96 carried about the exterior surface of the portion 88 of the mold 84. Numerous alternative methods of molding the interior of the shell body 12 will be apparent to those skilled in the art, the provision of collapsible segments as being an exemplary construction.

Thus, by virtue of the light-weight, plastic shell construction, together with the novel adapter head 34 (or 7%), a notably superior dual-purpose mortar shell is provided. The problems of rust, corrosion and sweating are obviated.

The adapter head 34 may be of molded plastic construction to receive a conventional super-quick M-52 fuse. Likewise, the mortar shell can be molded in con- ;entional sizes; e.g., 60 mm., 81 mm., 120 mm., and the ike.

From the foregoing description of the various embodiments of this invention, it is evident that the objects of this invention, together with many practical advantages are successfully achieved. While preferred embodiments of my invention have been described, numerous further modifications may be made without departing from the scope of this invention.

Therefore, it is to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted in an illustrative, and not in a limiting sense.

What is claimed is:

1. In a mortar shell the combination comprising an elongated unitary body portion composed of semi-rigid plastic material, said elongated body having its radially outer extent defined by a surface of revolution extending between first and second ends of said body, means defining an elongated chamber Within said body adapted to receive explosive material, said chamber being coaxial with said surface of revolution and communicating with the exterior of the body through the first end of said body, means defining a longitudinally elongated annular cavity within said elongated body, said cavity surrounding said chamber and being coaxial therewith, said cavity communicating with the exterior of the body through the first end of said body; a generally frusto-conical unitary adapter head having a first end of larger diameter and a second end of smaller diameter, means defining a longitudinal passage through said adapter head, means securing the adapter head to said body whereby said adapter head and said body are mutually coaxial, said adapter head first end engaging said body first end at the radially spaced annular portions thereof defined between said surface of revolution and said cavity means and between said cavity means and said chamber, said annular head first end thereby providing a closure for said cavity, said adapter head longitudinal passage being positioned to communicate with said chamber through said body first end; the second end of said elongated body being adapted to receive a tail assembly and the second end of said adapter head being adapted to receive a fuse assembly for communication with said chamber through said adapter head passage.

2. The combination as set forth in claim 1 additionally comprising a generally hollow cylindrical fragmentation sleeve slidably received within the annular cavity in said body and retained therewithin by said adapter head.

3, The combination as set forth in claim 2' wherein said hollow cylindrical fragmentation sleeve includes means defining a plurality of deep grooves extending circumferentially and longitudinally in the interior and exterior surfaces of said sleeve, said grooves being arranged so that each groove in the exterior surface of the sleeve has a coextensive counterpart groove in the interior surface of the sleeve.

4. The combination as set forth in claim 1 additionally comprising means defining an elongated annular cavity in said adapter head, said adapter head annular cavity surrounding said adapter head longitudinal passage and communicating with the exterior of said adapter head through the first end of said adapter head, and said adapter head annular cavity being coaxial with said body annular cavity and communicating therewith as an extension of said body annular cavity.

5. The combination as set forth in claim 4 additionally comprising a generally hollow cylindrical fragmentation sleeve slidably received within the closed annular space defined by the communication of the annular cavity in said body and said adapter head annular cavity.

6. The combination as set forth in claim 1 additionally comprising a plurality of longitudinally gas sealing rings integrally circumferentially extending from said surface of revolution of said body, the sealing ring most nearly adjacent said body second end having a rearwardly diverging portion arranged to be flexed outwardly into sealing engagement with a mortar barrel upon a discharge of propulsive gases in said barrel.

7. The combination as set forth in claim 1 additionally comprising an impact fuse threadably secured to said adapter head second end and a tail assembly threadably secured to said body portion second end.

References Cited by the Examiner UNITED STATES PATENTS 137,491 4/73 Senn 10267 189,358 4/77 Hotchkiss 102-67 2,070,946 2/37 Joyce 10249 2,283,224 5/42 Nichols 102-93 X 2,411,862 12/46 Arnold 102-67 2,772,635 12/56 Brandt 10278 X 2,872,865 2/59 Skaar 10256 2,920,563 1/60 De Caro 10295 X 3,058,424 10/62 Grandy 10294 FOREIGN PATENTS 617,519 4/61 Canada.

623,880 7/61 Canada. 1,218,345 12/59 France.

SAMUEL FEINBERG, Primary Examiner. S M E B D, E mi r.- 

1. IN A MORTAR SHELL THE COMBINATION COMPRISING AN ELONGATED UNITARY BODY PORTION COMPOSED FOR SEMI-RIGID PLASTIC MATERIAL, SAID ELONGATED BODY HAVING ITS RADIALLY OUTER EXENT DEFINED BY A SURFACE OF REVOLUTION EXTENDING BETWEEN FIRST AND SECOND ENDS OF SAID BODY, MEANS DEFINING AN ELONGATED CHAMBER WITHIN SAID BODY ADAPTED TO RECEIVE EXPLOSIVE MATERIAL, SAID CHAMBER BEING COAXIAL WITH SAID SURFACE OF REVOLUTION AND COMMUNICATING WITH THE EXTERIOR OF THE BODY THROUGH THE FIRST END OF SAID BODY, MEANS DEFINING A LONGITUDINALLY ELONGATED ANNULAR CAVITY WITHIN SAID ELONGATED BODY, SAID CAVITY SURROUNDING SAID CHAMBER AND BEING COAXIAL THEREWITH, SAID CAVITY COMMUNICATING WITH THE EXTERIOR OF THE BODY THROUGH THE FIRST END OF SAID BODY; A GENERALLY FRUSTO-CONICAL UNITARY ADAPTER HEAD HAVING A FIRST END OF LARGER DIAMETER AND A SECOND END OF SMALLER DIAMETER, MEANS DEFINING A LONGITUDINAL PASSAGE THROUGH SAID ADAPTER HEAD, MEANS SECURING THE ADAPTER HEAD TO SAID BODY WHEREBY SAID ADAPTER HEAD AND SAID BODY ARE MUTUALLY COAXIAL, SAID ADAPTER HEAD FORT END ENGAGING SAID BODY FIRST END AT THE RADIALLY SPACED ANNULAR PORTIONS THEREOF DEFINED BETWEEN SAID SURFACE OF REVOLUTION AND SAID CAVITY MEANS AND BETWEEN SAID CAVITY MEANS AND SAID CHAMBER, SAID ANNULAR HEAD FIRST END THEREBY PROVIDING A CLOSURE FOR SAID CAVITY, SAID ADAPTER HEAD LONGITUDINAL PASSAGE BEING POSITIONED TO COMMUNICATE WITH SAID CHAMBER THROUGH SAID BODY FIRST END; THE SECOND END OF SAID ELONGATED BODY BEING ADAPTED TO RECEIVE A TAIL ASSEMBLY AND THE SECOND END OF SAID ADAPTER HEAD BEING ADAPTED TO RECEIVE A FUSE ASSEMBLY FOR COMMUNICATION WITH SAID CHAMBER THROUG SAID ADAPTER HEAD PASSAGE. 